In general, raw vegetables have higher amounts of nutrients. However, this doesn’t mean you should eat only raw vegetables.
Cooking your vegetables can increase the bioavailibility of some nutrients. This means that some nutrients will become more available to your body through cooking.
The carotenoids (i.e beta carotene, lycopene) are a group of compounds found in fruits and vegetables that have antioxidant and other bioactive activites in the body. Foods containing carotenoids are known to protect against several cancers.
Cooking increases the absorption of carotenoids in your intestinal tract. A little added fat enhances this effect further because carotenoids need fat to be absorbed. So if you make marinara sauce, the heat and the olive oil added to the sauce will greatly increase the availability of the carotenoids in the fresh tomatoes. The lycopene in tomato paste is 4 times more available to the body than in fresh tomatoes.
For these reasons, I don’t believe it is necessary to consume only raw vegetables. Health benefits are conferred from both raw and cooked vegetables. Cover all your bases by eating a varied diet that includes cooked and raw vegetables.
If you want to retain as much nutrients as possible during the cooking process, don’t cook vegetables in large amounts of water that will be thrown out. Also do not over-cook your vegetables. If they start to turn dull in color, they have been cooking too long.
Hopefully this information has made you feel more at ease about your cooked vegetables!
Interesting/Fun Tip: peeling and chopping garlic releases the enzyme alliinase, which may provide several health benefits. Heating garlic without peeling the skin (as in roasted garlic), will deactivate this enzyme. If peeled/chopped garlic is allowed to sit 15-20 minutes prior to cooking, alliinase will not be destroyed in cooking.
World Cancer Research Fund/American Institute for Cancer Research: The Second Expert Report on Food, Nutrition, Physical Activity and the Prevention of Cancer, 2007.
Photo By: mjhoy